we have pieces from the world trade center and the pentagon, and the walk through metal detector that two of the terrorist walked through that morning. >> you can see the dust on this, still, from that day -- >> on the top? >> yeah, yeah. >> and in a city full of museums free to access, not everybody gets to see this hall, this space and these artifacts. mission hall not open to the public. in fact, we are the first camera crew to film this hall. >> this was a flag that flew over the gate in boston where american airlines flight 11 left from. and that's the first flight that went into the world trade center that morning. >> it gives a unique window to where tsa started and how far it has come. on 9/11, there were 33 federal air marshals all across the globe, and that number while classified now is in the thousands. >> you think about officers that work for tsa, and they could have been 8, 9, 10-year-old when september 11th happened, and it will be 12 years since it happened. when you think about that, and you think about the passage of time, it's important to just always remember. >>